SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '854a2dfd1037e3128991cfe18d4c76dd471f17972f2c1298f336e9157d29d297' 
  AND token = '3UO7APA0nHdOLHPgmQ/ofg6mdGMeLofmXYH9CUkn1ws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}